please help me infrared cordless headfone project

Z

zoyal

New Member
my name is zoyal student of telecomm.. and electronic engineering
i am doing project on infrared cordless headfone
i attach a circuit diagram of my project
in the circuit diagram
i have following problems
in the transmitter i can replace audio transformer with an voltage (step-up or step-down )transformer?
in the receiver circuit which IR photo-transistor(i.e op 550,pnz 107) ) will work if any please tell me its name.??
if some-one have any other circuit diagram please send it to me.....
 

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OP550A will sorta work, but it's designed for close-up work. An LTR-3208E which is in a T 1 3/4 case may work better for this. They are both in the 940nm range, you have to match the detector to the emitter LED's.

Afraid a power transformer may not work very well. But if you can find an old transistor radio or walkie-talkie or something that runs off a 9V battery, there's a good chance you can find that impedance-matching transformer in there. It will be connected to the speaker.
 
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That terrible circuit has many problems:
1) The first transistor in the transmitter has no bias so it is an audio rectifier producing horrible distortion.
2) The red LED in the transmitter is a lot more than only 0.65V and stops modulation of the IR LEDs.
3) The receiver has DC in the headphones which might mute them and maybe burn them.
4) The output transistor in the receiver is not biased properly. It might be saturated or be cutoff.

Most old circuits from that website in India don't work.
 
The red LED is fine, it just limits IR LED current to a 100ma peak.

But the circuit is very crude, at best. What website are you talking about?
 
And they sell these defective old circuits online, too, I see.

And here we are giving them a free online Help Desk.

 
If you really want to listen to good music with a cordless headphone don't use Ir. They are very noisy. Use a good Sennheiser product. I use the HDR85 late at night.
 
my name is salman i am making the project of infrered cordless headphone can u please tell me that this circuit will be workable with audio input from mp3 player
 
salman_telecom said:
my name is salman i am making the project of infrered cordless headphone can u please tell me that this circuit will be workable with audio input from mp3 player
Click to expand...
In this thread we say that the project is full of errors and is garbage.
 
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